The present invention relates to a laminar staple for mutually joining wood strips, particularly for joining at an angle profiled strips for manufacturing frames, frameworks and the like.
In the manufacture of picture frames, or wood frameworks for box-like containers and the like, the angled joining of the strips, rods or battens is performed by means of laminar staples which are driven astride the joining line formed by the mutually adjacent arrangement of the preliminarily chamfered ends of the strips.
In order to facilitate the driving of the staples, one of their sides has a cutting edge.
Considerable difficulties have been observed, with known staples, in keeping the strips mutually adjacent at the joining plane due to the non-uniformities of the cutting of the strips, due to the roughness of the cutting plane, and due to the imperfect linearity of the strips.
An attempt has been made to obviate these shortcomings by providing staples folded in the shape of a W (for example as shown in U.S. Pat. No. 29,957 and French patent no. 2318715) or provided with slightly converging ridges (as shown in British patent no. 1,165,482) so as to ensure that the heads of the strips are pressed with greater force against each other so as to avoid the forming of cracks. In practice it has been observed that the crack remains, although to a reduced extent, since during driving there is a greater contact pressure of the heads at the tapered part of the strips.
U.S. Pat. No. 4,681,498 in the name of the same Applicant also suggested to shape the staples in the form of a W so that the ridges diverge with respect to an intermediate portion both toward the cutting edge and toward the edge on which the striking mass acts. However, even in this case the improvement obtained was not conclusive.